Quantum noise in coupled atomic and molecular Bose-Einstein condensates

S. K. Giri

Ultracold atoms in the atomic Bose-Einstein condensate (ABEC) state can form molecular Bose-Einstein condensate (MBEC) through photoassociation.In the atom-molecule Bose-Einstein condensates (BECs), two or more atoms in the ABEC can combine to form a molecule in the MBEC and again a molecule from a MBEC can decompose to atoms in the ABEC.The Bose-stimulated Raman adiabatic passage is an efficient mechanism for conversion of an atomic BEC to a molecular BEC.A three-mode atom-molecule Bose-Einstein condensates system can be prepared through the photoassociative Bose-stimulated Raman adiabatic passage.In our system, three modes are one ABEC, one excited MBEC, and one stable MBEC.The intramodal interactions due to the  (3) nonlinearity is present in all three BEC modes along with ABEC-excited MBEC and excited MBEC-stable MBEC intermodal couplings.The quantum mechanical Hamiltonian of the system is constructed considering all three intraspecies interactions and intermodal couplings among the modes.The Hamiltonian of the system is solved analytically using a special intuitive approach which is more general and gives more accurate result than the well-known short time approximation method.The correctness of the solution is verified through the equal time commutation relation.Staring from a three-mode composite coherent state we compute the time evolution of the field annihilation operators of all three modes in presence of all possible interactions and couplings.Using these solutions, we investigate the quantum entanglement properties of the system for all three two-mode combinations.Entanglement is found for two combinations of modes, where as one combination is always separable.Also, we study the dependence of the entanglement properties of the system with the interaction and coupling constants.

Michael J. Steel, M. K. Olsen, Lev I. Plimak +5 more

Oleś, Bartłomiej

S. A. Gredeskul, Yuri S. Kivshar

We study the stability of coherent atomic-molecular states of hybrid Bose-Einstein condensates in the framework of the parametrically coupled Gross-Pitaevskii equations with a weak 'short-correlated' noise, also taking into account the self-interaction effects described by the cubic nonlinearity. We show that the stationary states of the hybrid atomic-molecular condensates are much more robust against the effect of noise than the condensate in the critical regime, describing a complete transformation of the atomic fraction into a molecular condensate, where instability develops essentially faster, with the characteristic time proportional to the logarithm of the noise amplitude.

Ali Tozar, Fatema Alkhattab

P. D. Drummond, Karen V. Kheruntsyan, Hao He

We analyze the coherent formation of molecular Bose-Einstein condensate (BEC) from an atomic BEC, using a parametric field theory approach. We point out the transition between a quantum soliton regime, where atoms couple in a local way to a classical soliton domain, where a stable coupled-condensate soliton can form in three dimensions. This gives the possibility of an intense, stable atom-laser output.